Anritsu BTS Master MT8221B, Руководство пользователя

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8-3 LTE/TD-LTE EMF Menu EMF (Option 444)
8-8 PN: 10580-00234 Rev. V 3GPP MG
When the extrapolation factor is turned Off, the Field Strength number is the measured
Channel Power in a 1.4 MHz bandwidth. Changing the bandwidth (BW) setting in the Setup
menu does not change this number.
If the extrapolation factor is On, the Field Strength (E
max
) is computed as follows:
E
max
= E
cp
× N
cp
where E
cp
is the RMS value of the channel power recorded in each axis and N
cp
is the number
of subcarriers divided by 72. The number of subcarriers can be provided by the network
operator or can be calculated from
Table 8-1 . The selected channel bandwidth (
BW
key in the
instrument Setup main menu) determines the number of subcarriers. The default BW is
1.4 MHz.
Assuming that all subcarriers in the BW setup are at the same power level, the Field
Strength value for other BW setups can be extrapolated based on the Channel Power in
1.4 MHz BW. The Field Strength cell labels in the table are updated with an
Ex , such as Field
Strength (Ex Avg), to indicate the extrapolation factor has been applied. See Figure 8-8
on page 8-9 .
The displayed values are measurement results from the BW setup made prior to starting the
measurement. Changing the BW setup, hence the extrapolation factor, after the
measurement is complete has no effect on the currently displayed values.
If a valid Cell ID is obtained even once during the entire measurement period, an entry will
be made in the table. “--” indicates an invalid result. A maximum of six cell IDs can be
detected. The Total row sums the isotropic numbers for the selected display parameter across
Cell IDs.
Table 8-1. Field Strength Numbers
Channel Bandwidth (MHz) Subcarriers
1.4 72
3 180
5 300
10 600
15 900
20 1200